Another summer field season has now come and gone! This summer I returned to Solon Dixon Forestry Education Center in Alabama (one of my favourite spots on earth!) to continue my research on how stress during gestation influences the offspring of eastern fence lizards (Sceloporus undulatus).
Last year, we investigated how physiological stress during gestation (at the level of a non-lethal predator encounter – for example, when a lizard encounters a couple of toxic fire ants, but isn’t killed by the ants) affects survival of mothers, and how many of their eggs successfully hatch. You can read more about this experiment, and the fieldwork that went into it, here (and stay posted for the published results soon!).
This year I wanted to build on these results and ideas to test how maternal stress influences the offspring that do hatch and make it out into the world. Do they themselves then cope better with a stressful environment, having been “primed” for it by their mothers (the “environmental matching” hypothesis)? Or are offspring born to stressed mothers poorer in quality, and less likely to survive in the wild, regardless of how stressful their environment is? In order to test these ideas, we first made the long trip south to collect gravid females from south Alabama early in the summer, and to build experimental enclosures in which to eventually release their offspring. I then repeated the maternal stress treatment from last year and once again became a lizard mama as I followed the females from laying their eggs, to incubating the eggs, and eventually seeing these bite-sized babies hatch out!
Once they hatched, the offspring went into the enclosures that we’d built. These enclosures were designed to test whether maternal stress programs offspring to be able to better deal with a stressful environment. The enclosures either contained a key stressor (invasive fire ants), or were fire ant-free. Each day I conducted a mini-census, walking through enclosures to look for each lizard – as you can see in the video below, babies were marked so I could tell exactly who was present each day (and so, which lizards survived, and which didn’t). I also observed their behaviour, and how they used the habitat available to them (for example, did offspring from stressed/non-stressed mothers differ in whether they liked to be out in the open, like the lizards you see in the video – or did they hide more?).
After a great summer (if measuring 200+ baby lizards isn’t a metric of a great summer, I don’t know what is), I’m now back at Penn State with a box of data to work through. I’m excited to report back on what I found in the coming months – so stay tuned!